There is currently no universally accepted or understood measurement methodology for lung sounds. Quantitative measures of lung sounds transduced at the skin surface can be corrupted non-trivially by artifacts associated with mechanical interactions of the chest wall with the transducer. We have developed a method for relating the corrupted transducer output signal to idealized measures of lung sounds which are independent of the mechanical properties of the transducer. An essential parameter in that method is the mechanical impedance of the chest wall. Specifically, we propose to measure the mechanical impedance of the chest wall from 100 to 3000 Hz, as a function of position, lung volume, and contacting diameter, and static load. This will be accomplished in normal adult using an impedance head, mechanical shaker, and transient excitation. This data will be employed to develop criteria and methodologies for lung sound measurement.